docs: def update_paths(self):
          """ Check sys.modules for paths to add to our path set."""
          new_paths = []
          with self.lock:
              for path in expand_source_paths(iter_module_paths()):
                  if path not in self.paths:
                      self.paths.add(path)
                      new_paths.append(path)
          if new_paths:
              self.watch_paths(new_paths)